Process for the preparation of polyol polymer dispersions

ABSTRACT

Polymer polyols and polymer-modified polyols having substantially no transition metal content in the polyol continuous phase may be prepared from encapsulative double metal cyanide complex-catalyzed polyoxyalkylene polyether base polyols without substantial removal of double metal cyanide complex catalyst residues from the base polyol and subsequent in situ polymerization of one or more polymerizable monomers.

TECHNICAL FIELD

The present invention pertains to a process for the manufacture ofpolymer polyols by the in situ polymerization of vinyl monomers and tothe manufacture of polymer-modified polyols by the in situpolymerization of polyisocyanates and isocyanate reactive monomers, bothtypes of in situ polymerization conducted in the presence of apolyoxyalkylene polyether base polyol. More particularly, the presentinvention pertains to an improved process for manufacture of polymerpolyols and polymer-modified polyols having substantially no catalystresidues in the continuous polyol phase wherein certain double metalcyanide complex-catalyzed polyoxyalkylene polyether polyols are used asthe base polyol, and the in situ polymerization are conductedsubsequently without removal of double metal cyanide complex catalystresidues. Polyurethane foams prepared from such polyol polymerdispersions surprisingly require less catalyst concentration thansimilar foams prepared from dispersions employing conventional polyolsas base polyols.

BACKGROUND ART

Polymer polyols, as that term is used herein, refers to polyvinylpolymer dispersions prepared by the in situ polymerization of one ormore vinyl monomers in a polyoxyalkylene "base" polyol. Polymer-modifiedpolyols, as that term is used herein, refers to polyoxyalkylenepolyether polyols having a dispersed phase of a urea or urethane/ureapolymer prepared by the in situ polymerization of a diisocyanate orpolyisocyanate with an isocyanate-reactive monomer, preferably anamino-functional monomer such as an alkanolamine, diamine, or the like.The majority of such polymer polyols and polymer-modified polyols areused in the polyurethane field for diverse applications, including cellopeners and hardness enhancers for polyurethane foam, and as reinforcingadditives for a variety of microcellular and non-cellular polyurethanes.

The manufacture of polymer polyols is by now well known, and may involvebatch, semi-batch, and fully continuous processes. In all of theseprocesses, one or more vinyl monomers such as acrylonitrile and styreneare polymerized in situ in one or more base polyols, with or without thepresence of an added stabilizer. The amount of monomer(s) fed to thereactor is selected to achieve the desired vinyl polymer solids contentin the final polymer polyol product. The solids level may range from aslittle as 5 weight percent to upwards of 60 weight percent, however, itis most economical to produce polymer polyols at relatively high solidsloadings even when a low solids product is desired. If a lower solidscontent polymer polyol is desired, the solids content may be lowered bydilution of the higher solids polyol with further amounts of the samebase polyol or other non-polymer polyol, or by blending with a polymerpolyol of lesser solids content. The base polyol functionality isdictated by the particular polyurethane end-use desired, and maytypically involve nominal functionalities of two to eight. The detailsof polymer polyol manufacture will be presented hereafter.

The manufacture of polymer-modified polyols is also by now well known.The two most common polymer-modified polyols are the so-called PIPA(PolyIsocyanate PolyAddition) polyols and the PHD (PolyHarnstoffDispersion) polyols. Both these polymer-modified polyols and others areprepared by the addition polymerization of an isocyanate, for example adi- or polyisocyanate, with an isocyanate-reactive monomer, preferablyan amino-functional compound: an alkanolamine in the case of PIPApolyols, and a di- or polyamine in the case of PHD polyols. Mixtures ofthese isocyanate reactive monomers as well as reactive diols may also beused. The reactive monomers are polymerized in situ in a polyoxyalkylenepolyether polyol which forms the continuous phase of thepolymer-modified polyol. In many cases, a portion of the polyolcontinuous phase becomes associated with the polymer phase by reactionwith isocyanate groups. More detailed description of polymer-modifiedpolyols is presented hereinafter.

In both polymer polyols and polymer-modified polyols, the monomers aregenerally initially soluble in the polyol continuous phase, as are ingeneral the initial low molecular weight oligomers. However, as themolecular weight of the polymer phase grows, the polymer becomesinsoluble, forming small particles which rapidly coalesce and/oragglomerate to larger particles in the submicron to several micronrange. Hereinafter, the term "polymer polyol" will refer to dispersionsof vinyl polymers, "polymer-modified polyol" to polyurea,polyurethaneurea, or other isocyanate-derived polymer dispersions, andthe term "polyol polymer dispersions" will refer to both of thesecollectively.

The base polyols used in preparing polyol polymer dispersions generallycontain a high proportion of polyoxypropylene moieties. Polyoxypropylenepolyether polyols are conventionally prepared by the base-catalyzedoxyalkylation of a suitably functional initiator molecule with propyleneoxide or a mixture of propylene oxide and ethylene oxide. Duringbase-catalyzed oxypropylation, a competing rearrangement of propyleneoxide into allyl alcohol continually introduces this unsaturated monolinto the polymerization reactor. The allyl alcohol acts as an additionalinitiator, and being monofunctional, lowers the actual functionality ofthe polyol. The continued creation of low molecular weightmonofunctional species also broadens the molecular weight distribution.As a result of these effects, the practical upper limit ofpolyoxypropylene polyether polyols equivalent weight is c.a. 2000 Da(Daltons).

For example, a 4000 Da molecular weight base-catalyzed polyoxypropylenediol may contain 0.07 to 0.12 meq. unsaturation per gram polyol,amounting to from 25-40 mol percent of monol. As a result, the polyolnominal functionality of two is reduced to actual functionalities ofc.a. 1.6 to 1.7 or less. Unsaturation is generally measured inaccordance with ASTM test D-2849-69 "Testing Urethane Foam Polyol RawMaterials."

Lowering the oxypropylation temperature and decreasing the amount ofbasic catalyst allows for some reduction of unsaturation, but at theexpense of greatly extended reaction time which is not commerciallyacceptable. Moreover, the reduction in unsaturation is but slight. Useof alternative catalyst systems, for example cesium hydroxide ratherthan the more commonly used sodium or potassium hydroxides; strontium orbarium hydroxides; dialkyl zinc; metal naphthenates; and combinations ofmetal naphthanates and tertiary amines have all been proposed. However,the unsaturation is generally reduced only to about 0.03 to 0.04 meq/gby these methods, still representing 10-15 mol percent monol. In allthese cases, the catalyst residues must be removed prior to the in situpolymerization of vinyl or other monomers to produce polyol polymerdispersions. Basic catalysts are generally removed by adsorption withmagnesium silicate followed by filtration, by neutralization followed byfiltration, or through the use of ion-exchange techniques.

In the 1960's, double metal cyanide catalysts such as complexes of zinchexacyanocobaltate were found to be useful in a variety ofpolymerization reactions, as evidenced by U.S. Pat. Nos. 3,427,256,3,427,334, 3,427,335, 3,829,505, 3,941,849, and 4,242,490. Inpolymerization of propylene oxide, such catalysts were found to producepolyols with unsaturation in the range of 0.02 meq./g. However, eventhough relatively active catalysts, their cost relative to activity wasquite high. In addition, catalyst removal was problematic. Refinementsin double metal cyanide complex catalysts have led to catalysts withsomewhat higher activity, as evidenced by U.S. Patent Nos. 4,472,560,4,477,589, 4,985,491, 5,100,997, and 5,158,922. These catalysts,generally glyme complexes of zinc hexacyanocobaltate, were effective inpreparing polyoxypropylene polyols with unsaturation levels of c.a.0.015 to 0.018 meq/g. Despite being more active than the priorcatalysts, the cost of these improved catalysts, in addition to thedifficulties associated with catalyst removal, again prevented any largescale commercialization.

Recently, however, exceptionally active double metal cyanide complexcatalysts have been developed at the ARCO Chemical Co., as evidenced byU.S. Pat. No. 5,470,813 and U.S. Pat. No. 5,482,908, herein incorporatedby reference. In addition to their much higher activity as compared toprevious double metal cyanide complex catalysts, these catalysts havefurther been shown suitable for producing polyoxypropylene polyols withmeasured unsaturation in the range of 0.003 to 0.007 meq/g. Not only isthe measured unsaturation exceptionally low, but moreover, despite thefact that unsaturation is generally accepted as a measure of monolcontent, lower molecular weight species are not detected by gelpermeation chromatography. The polyoxypropylene polyols are trulymonodisperse, having a very narrow molecular weight distribution.Despite being much more active catalysts than prior catalysts and beingmore susceptible to simple filtration for catalyst removal, thenecessity to finely filter or otherwise remove catalyst residues priorto use as base polyols for polyol polymer dispersion productionundesirably increases processing time.

In Japanese published application H2-294319 (1990), double metal cyanidecomplex catalysts were used to prepare polyoxypropylene polyolsfollowing which the double metal cyanide catalyst residues weredenatured by adding alkali metal hydroxide which then served as theoxyalkylation catalyst for capping the polyoxypropylene polyols withoxyethylene moieties. Following removal of the catalyst residues, highprimary hydroxyl content polymer polyols were prepared in a conventionalmanner. Similar polymer polyols prepared by in situ polymerization inoxyethylene capped polyoxypropylene polyols are disclosed in U.S. Pat.Nos. 5,093,380 and 5,300,535.

In Japanese published application 5-39428 (1993), unspecific zinchexacyanocobaltate catalysts were used to prepare polyoxypropylenepolyols which were then used as base polyols for polymer polyolmanufacture, with or without further addition of double metal cyanidecatalyst as a vinyl polymerization catalyst. However, the presence oflarge amounts of double metal cyanide catalyst residues in the polymerpolyol product, even if they did not affect subsequent in situ vinylpolymerization, is undesirable. In the food processing industry andmedical prostheses industries, for example, heavy metal ion content mustbe minimal.

J. L. Schuchardt and S. D. Harper, "Preparation Of High Molecular WeightPolyols Using Double Metal Cyanide Catalysts," 32ND ANNUAL POLYURETHANETECHNICAL MARKETING CONFERENCE, Oct. 1-4, 1989, discloses that doublemetal cyanide complex catalyst residues can increase the viscosity ofisocyanate-terminated prepolymers prepared from polyols containing suchresidues, this viscosity increase believed due to allophanate formation.Herrold et al. in U.S. Pat. No. 4,355,188 and the many other patentsdirected to removal of catalyst residues, e.g., U.S. Pat. Nos.3,427,256, 5,248,833, 4,721,818, 5,010,047, and 4,987,271 attest to thecommercial significance of double metal cyanide catalyst removal.

It would be desirable to provide a method of preparing polyol polymerdispersions from double metal cyanide catalyzed polyoxypropylenepolyether polyols without the necessity of removing or denaturing doublemetal cyanide complex catalyst residues, without such catalyst residuesappearing in the continuous polyol phase of the polyol polymerdispersion. It would be further desirable to prepare polymer polyolswhich are white or off-white in color.

SUMMARY OF THE INVENTION

It has now been surprisingly discovered that polyol polymer dispersionsmay be prepared from certain double metal cyanide complex-catalyzedpolyoxypropylene polyether polyols without removing the double metalcyanide complex catalyst residues, while obtaining polyol polymerdispersions containing only exceptionally low levels of catalystresidues in the continuous polyol portion of the polyol polymerdispersion. The polymer polyols of the subject invention are generallywhite to off-white in color, and may be stored without concern ofgradual precipitation of double metal cyanide complex residue solids orgeneration of carbonyl group-containing polyether polyol decompositionproducts. Catalyst levels in polyurethane foam formulations employingpolyol polymer dispersions of the subject invention can unexpectedly bereduced from levels required for preparing foam from dispersionsemploying conventional polyols as the base polyol.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The polyoxyalkylene polyols used as base polyols for the subsequentmanufacture of polyol polymer dispersions include at least onepolyoxyalkylene polyether polyol prepared by the polymerization ofpropylene oxide onto one or more initiator molecules of suitablefunctionality, optionally in conjunction with one or more alkyleneoxides other than propylene oxide, in the presence of an encapsulativedouble metal cyanide complex catalyst as hereinafter defined. Thealkylene oxides other than propylene oxide which may optionally be usedin conjunction with the latter include, but are not limited to, ethyleneoxide, 1,2- and 2,3-butylene oxide, styrene oxide, C₅₋₂₀ α-olefinoxides, epichlorohydrin, chlorinated butylene oxides, and the like.Ethylene oxide is particularly preferred. When an additional alkyleneoxide other than ethylene oxide is used together with propylene oxide,the additional alkylene oxide may be added to the polymerization at anystage, either alone, or with additional propylene oxide, to form block,random, or block/random polyoxyalkylene polyether polyols. However, whenethylene oxide is used as the additional alkylene oxide, the ethyleneoxide must be added together with propylene oxide or other higheralkylene oxide to form random or block/random polyoxyalkylene polyols.Polyoxyalkylation with ethylene oxide alone has been found to result inproducts believed to contain large quantities of polyoxyethylene insteadof the desired oxyethylene blocks or caps in the polyoxyalkylene polyol.

Suitable initiator molecules include the dito octafunctional,conventional initiator molecules, for example, ethylene glycol,propylene glycol, glycerine, trimethylolpropane, pentaerythritol,sorbitol, sucrose, and the like. However, it has been found that doublemetal cyanide complex-catalyzed oxyalkylation of low molecular weightinitiators, particularly low molecular weight vicinal glycol initiatorssuch as the foregoing, results in low initial oxyalkylation rates aswell as an extended "induction period" before significant catalyticactivity occurs. Thus, it is preferable to use oligomericpolyoxyalkylation products of the above or other monomeric initiators asinitiators for preparing the base polyoxyalkylene polyol.

Suitable oligomeric initiators may be prepared by conventional, basecatalyzed oxyalkylation of monomeric initiators, or by catalysis withalternative catalysts such as diethylzinc, calcium naphthenate, and thelike. The particular catalyst is not critical, however, when basiccatalysts are used, the catalyst residues should be removed from theoligomeric initiator by conventional treatment prior to continuedoxyalkylation employing double metal cyanide complex catalysts;otherwise, the latter may be inactivated. The oligomeric initiators maycomprise monomeric initiators oxyalkylated with propylene oxide,mixtures of propylene oxide and ethylene oxide or another alkyleneoxide, higher alkylene oxides, or all ethylene oxide. Preferable areoligomeric initiators prepared from all propylene oxide or mixtures ofpropylene oxide and ethylene oxide. The oligomeric initiators preferablyhave equivalent weights of from 100 Da to 1000 Da, preferably from 150Da to 500 Da. Molecular weights and equivalent weights herein in Da(Daltons) are number average molecular weights and number averageequivalent weights, respectively, unless otherwise designated.

The oxyalkylation conditions for preparation of the base polyol arethose conventionally used in double metal cyanide complex oxyalkylation.The initiator, preferably an oligomeric polyoxyalkylene polyolinitiator, is charged to an agitated reactor, the double metal cyanidecomplex catalyst added, and the reactor purged with nitrogen. Propyleneoxide is added at the desired oxyalkylation temperature, generally from50° C. to 160° C., more preferably from 70° C. to 130° C., and thereactor pressure monitored until a pressure drop is observed, indicatingthe end of the induction period. Additional propylene oxide, optionallyin conjunction with other alkylene oxide, is then added until thedesired molecular weight is achieved. Reaction pressure is generallykept below 6 bar. Following alkylene oxide addition, the reactor ismaintained at the oxyalkylation temperature for a period to allowunreacted alkylene oxide to react, the reactor vented, and any remainingalkylene oxide stripped off at modest to low vacuum, optionally with theuse of a nitrogen stream.

In the past, following preparation of polyoxyalkylene polyols by theabove method, the polyol product has been treated to remove residualdouble metal cyanide catalyst, by filtration, denaturing, treatment withchelating agents, or combinations of these methods. However, in thepractice of the subject invention, it is not necessary to remove thedouble metal cyanide complex catalyst residues to the extent necessaryfor conventional polyether polyols, provided an encapsulative doublemetal cyanide complex catalyst is used. It would not depart from thespirit of the invention to rapidly filter the polyoxyalkylene polyol,for example, through a coarse filter to remove a portion of the catalystresidues, or to store the polyol in a non-agitated tank and allow aportion of the catalyst residues to settle out. However, in either case,the amount of residual double metal cyanide complex residues present inthe base polyol prior to in situ vinyl polymerization, will normallyexceed the limits detectable by Inductively Coupled Plasma sampleanalysis or other equivalent means of analysis, this limit generallybeing c.a. 1 ppm. Preferably, the major portion of double metal cyanidecomplex catalyst residue is not removed from the base polyol.

For example, a polyoxypropylene polyol prepared with an encapsulativezinc hexacyanocobaltate complex catalyst at a catalyst concentration of250 ppm in the finished polyol, after simple filtration or normalsetting upon storage, may contain 47 ppm Zn and 16 ppm Co. Followingpolymer polyol preparation, the levels of Zn and Co in the polyolpolymer dispersion continuous phase may be reduced to 2 ppm Zn and <1ppm Co, levels which are commercially acceptable. Preparation of basepolyols with encapsulative double metal cyanide catalysts at lowercatalyst levels and/or by more thorough filtration, with or withoutadditional methods of catalyst removal, may result in Zn and Co levelsof, for example 3 ppm and 2 ppm, respectively prior to polymerization toprepare the dispersed phase. While these transition metal levels arelow, they may be lowered further by in situ polymerization to formdispersed polymer phase in which the catalyst residues are concentratedin the dispersed phase.

Thus, whether the initial transition metal content is high or low, it islowered further by the process of the subject invention, provided thatan encapsulative double metal cyanide complex catalyst is utilized. Itis most surprising that under the same conditions, non-encapsulativedouble metal cyanide catalysts remain substantially in the continuousphase. The subject process allows encapsulative double metal cyanidecomplex catalyst residues to be simply left in the polyol without anypost-treatment catalyst removal, or post-treatment which removes only aportion of catalyst residues, for example a coarse, rapid filtrationwhich by itself would not be suitable for purification of non-polymer,double metal cyanide complex catalyzed polyols.

The base polyols suitable for use in the process of the subjectinvention may contain from 4 ppm transition metal content to well overseveral hundred ppm transition metal content. Preferably, the basepolyols contain from 4 ppm to 100 ppm, more preferably from 5 to 50 ppm,and most preferably, from 10-40 ppm transition metal content. Catalystconcentrations of 20 ppm or more relative to base polyol are the generalrule, and quite suitable for use in the subject invention. Preferably,the base polyol is not treated to remove catalyst residues. However, iftreated, filtration to remove catalyst residues such that the transitionmetal content is greater than about 2 ppm is one preferable means oftreatment, and sedimentation followed by separation of catalyst-depletedsupernatant constitutes a second preferable means of treatment. Thecatalyst remaining in the continuous phase following in situ dispersedphase polymerization preferably contains less than 4 ppm totaltransition metals, more preferably less than 3 ppm, and most preferablyless of each metal than a lower limit of detection of c.a. 1 ppm. Theadvantageous results of the subject process may also be characterized bythe degree of catalyst removal from the base polyol into the dispersedpolymer phase, regardless of the continuous phase transition metalcontent. Preferably, 60% or more of the transition metal content of thebase polyol is partitioned into the dispersed polymer phase, morepreferably 75% or more, and most preferably about 90% or more on aweight basis. Both a high of percentage partitioning and minimalcontinuous phase transition metal content are of course most desirable.

The polyol polymer dispersions prepared by the subject process areunique products, in that double metal cyanide complex catalyst residuesare present in the polymer polyol or polymer-modified polyol as a whole,but concentrated in the dispersed polymer phase and largely absent fromthe continuous polyol phase. Such polyol polymer dispersions have notbeen previously disclosed.

The double metal cyanide complex catalysts useful in the subjectinvention are encapsulative double metal cyanide catalysts. When suchcatalysts are utilized, the catalyst residues become associated with thepolymer particle dispersed phase, and are removed from the continuouspolyoxyalkylene polyether polyol phase. While not wishing to be bound byany particular theory, it is believed that the polymer particlesactually encapsulate the double metal cyanide complex catalyst residues.It is possible that the polymerizable monomers preferentially polymerizeon or proximate to the double metal cyanide complex residues,surrounding the residue with polymer, or that double metal cyanidecomplex particle residues serve as nucleation sites for polymer particleagglomeration or coagulation, or that the polymer particles oragglomerates serve as adsorbent sites for the catalyst residues.

By whatever mechanism or combination of mechanisms which is/areoperable, the net result is that double metal cyanide complex residuesare removed from the continuous polyoxyalkylene polyether polyol phase.When the discontinuous polymer phase is separated from the polyol phaseby means of filtration or centrifugation, it is found that when anencapsulative double metal cyanide complex catalyst is used, the polymerparticles contain virtually all catalyst residues and the polyol phasecontains little or none. The measured amounts of transition metals, forexample, zinc and cobalt, in the continuous polyoxyalkylene polyolcomponent are close to or below the common limits of detection. Thus,the term "encapsulative double metal cyanide catalyst" refers to adouble metal cyanide catalyst which becomes associated with the polymerparticles of the dispersed polymer phase in polyol polymer dispersionssuch that no substantial amount of double metal cyanide catalyst remainsin the continuous polyol phase. At least 75 weight percent of doublemetal cyanide complex residues, as measured by total Zn/Coconcentrations, should preferably be removed from the continuous polyolphase.

It has been surprisingly found that the double metal cyanide complexcatalysts utilized in the prior art, zinc hexacyanocobaltate.glymecatalysts, are not encapsulative double metal cyanide catalysts.Residues of such catalysts, as shown by Comparative Example 5 herein,remain in most substantial part in the continuous polyol phase. Todetermine whether any particular double metal cyanide complex catalystis an encapsulative double metal cyanide complex catalyst, a simple testmay be performed. In this test, the double metal cyanide complexcatalyst under consideration is used to prepare a polyoxyalkylenepolyether base polyol by oxyalkylating a 200-500 Da equivalent weightoligomeric polyoxypropylene initiator in the presence of from 25 ppm to250 ppm double metal cyanide complex catalyst based on the weight of thebase polyol product. The amounts of transition metals in the polyolproduct, for example Co and Zn, are measured, for example by InductivelyCoupled Plasma techniques, and a polymer polyol prepared by the in situpolymerization of a 1:2 mixture of acrylonitrile and styrene in thepresence of an effective amount of a vinyl polymerization initiator, forexample 0.5 weight percent azobisisobutryronitrile, to form a polymerpolyol having a dispersed phase which constitutes from 20 to 50 percentby weight of the polymer polyol product. The dispersed polymer phase isthen separated from the continuous polyol phase and the transition metalcontent of the polyol phase determined. If the polyol phase containsless than 25% total transition metal as compared to the amount presentin the base polyol prior to in situ vinyl polymerization, or ifregardless of the relative percentage the transition metal contents ofthe continuous polyol phase are lowered from higher levels toapproximately the limits of detection or below (1-2 ppm), then thecatalyst is an encapsulative double metal cyanide complex catalyst. Theencapsulative double metal cyanide complex catalysts identified by thistest may be used to prepare both the polymer polyols andpolymer-modified polyols of the subject invention.

Suitable encapsulative double metal cyanide complex catalysts aredisclosed in U.S. Pat. No. 5,470,812 and U.S. Pat. No. 5,482,908, whichare herein incorporated by reference. Examples of encapsulative doublemetal cyanide complex catalysts are given herein in Examples 1-6. Whilethe descriptions herein and test methodology have been illustrated bythe use of the preferred zinc hexacyanocobaltate complex catalysts, itis to be understood that encapsulative double metal cyanide complexes ofother metals may be used as well. In such cases, the definitions,ranges, limitations, etc., presented herein with respect to Co and Znshould be equated with the same limitations for the particular metalsinvolved, for example Zn and Fe for zinc hexacyanoferrates; Ni and Fefor nickel hexacyanoferrates; and Fe and Cr for iron (II)hexacyanochromate. Due to their generally higher catalytic activity,complexes containing zinc as the cation and cobalt in thecyanide-containing anion are highly preferred. For purposes ofdefinition of catalyst residues in ppm, a theoretical metal atomicweight of 62 is assumed. The corresponding ppm level for any given metalmay be found by multiplying a particular metal residue level by theappropriate atomic weight/theoretical metal atomic weight ratio. Forexample, if the metal were vanadium with an atomic weight ofapproximately 51 amu, a 5 ppm metal residual level would become 5ppm×(51/62).

Preferred complexing agents for preparing the encapsulative double metalcyanide complex catalysts are t-butanol and combinations of t-butanolwith one or more oligomeric polyoxyalkylene polyether polyols,preferably polyether polyols at least partially terminated with atertiary hydroxyl moiety. The polyether polyol complexing agentspreferably have equivalent weights greater than 200 Da, more preferablygreater than 500 Da, and most preferably in the range of 1000 Da to 3000Da. The encapsulative double metal cyanide complex catalysts are, ingeneral, non-stoichiometric complexes which are substantially amorphousas shown by the virtual absence of sharp lines in their X-raydiffraction spectra corresponding to crystalline double metal cyanideitself, i.e., zinc hexacyanocobaltate in the case of zinchexacyanobaltate complex catalysts. The catalysts also, in general, havemeasurably greater particle sizes than prior art catalysts, such as theconventionally prepared zinc hexacyanobaltate.glyme catalysts.Preferably used are substantially amorphous zinc hexacyanocobaltatecomplex catalysts exhibiting substantially no sharp peak in an X-raydiffraction pattern at a d-spacing of approximately 5.1.

The in situ vinyl polymerization used to prepare polymer polyols isconventional except for the presence of the encapsulative double metalcyanide complex residues. Examples of suitable polymer polyolpreparation may be found in U.S. Pat. Nos. 3,304,273, 3,383,351,3,652,639, 3,655,553, 3,823,201, 3,953,393, 4,119,586, 4,524,157,4,690,956, 4,997,857, 5,021,506, 5,059,641, 5,196,746, and 5,268,418,which are herein incorporated by reference. Either batch processes,semi-batch, or fully continuous methods of preparation may be used.Continuous processes are preferred.

In the semi-batch process, a reactor vessel equipped with an efficientmeans of agitation, for example an impeller-type stirrer orrecirculation loop, is charged with from 30% to 70% of total basepolyol. To the reactor is then added the polymerizable vinyl monomersdissolved in additional polyol. Vinyl polymerization catalyst may beadded to the vinyl monomer solutions, which are maintained at relativelylow temperature prior to addition to the reactor, or may be added as aseparate stream. The reactor itself is maintained at a temperature suchthat the polymerization catalyst is activated. In most cases, the vinylpolymerization catalyst is a free radical polymerization initiator.Following addition of the desired quantity of vinyl monomers, thereactor is allowed to "cook out" to substantially complete vinylpolymerization, following which residual unreacted monomers may beremoved by stripping.

A continuous process may be implemented in one or more reactors inseries, with the second reactor facilitating substantially completereaction of vinyl monomers with continuous product takeoffs, or may beperformed in a continuous tubular reactor with incremental additions ofvinyl monomers along the length of the reactor.

The preferred vinyl monomers are styrene and acrylonitrile. However,many vinyl monomers are suitable, non-limiting examples beingmethylacrylate, methylmethacrylate, α-methylstyrene, p-methylstyrene,methacrylonitrile, vinylidene chloride, and the like. Lists of suitablevinyl monomers may be found in the references previously cited. Mixturesof vinyl monomers are advantageously used, preferably mixtures ofacrylonitrile and styrene in weight ratios of 10:1 to 1:10, morepreferably 1:4 to 4:1, and most preferably 1:1 to 1:3. Mixtures of vinylmonomers comprising about 50 weight percent or more of styrene with oneor more monomers other than styrene are particularly preferred.

The polymerization catalyst is preferably a free radical polymerizationinitiator such as an azobisalkylnitrile, for exampleazobis(isobutryonitrile) (AIBN), azobis(4-cyanovaleric acid),azobis(dimethylvaleronitrile), preferably AIBN; peroxy compounds, forexample, peroxyesters and peroxyketones, and the like. Redoxpolymerization initiators may also be used.

The in situ vinyl polymerization is preferably conducted in the presenceof a stabilizer or stabilizer precursor. Stabilizer precursors maycomprise one or more polyoxyalkylene moieties bonded to a group whichcan participate in vinyl polymerization, preferably a reactive,unsaturated ethylenic group. Examples of stabilizers and stabilizerprecursors are contained in the previously cited patents, and includepolyetherester polyols prepared by reacting maleic anhydride with apolyoxyalkylene polyol and capping the remaining free carboxyl group ofthe half-ester with an alkyl or polyoxyalkyl group; the reaction productof isocyanatoethylacrylate or like compounds with a polyoxyalkylenepolyol; or the reaction product of other unsaturated isocyanates, i.e.,TMI, 1-(1-isocyanato-1-methylethyl)-3-(1-methylethenyl)benzene with apolyoxyalkylene polyol. The stabilizer precursor may be present in thereaction mixture to the extent of less than 0.01 to about 0.3 molpercent, preferably 0.01 to about 0.1 mol percent.

Reaction moderators and polymer control agents may also be present.Reaction moderators fall within the general class of chain transferagents, and are believed to limit the molecular weight of the vinylpolymers produced. Examples of reaction moderators include alkanols suchas isopropanol and isobutanol; mercaptans such as dodecylmercaptan;halogenated hydrocarbons, particularly those containing bromine and/oriodine, and the like. Further examples of reaction moderators may befound in the patents previously cited. Polymer control agents includelow molecular weight liquids not conventionally viewed as chain transferagents, as described in U.S. Pat. No. 4,652,589, herein incorporated byreference. Suitable polymer control agents include water, cyclohexane,and benzene.

As previously discussed, polymer-modified polyols are prepared by insitu polymerization of one or more di- or polyisocyanates withisocyanate-reactive components, which may be a portion of the isocyanateitself. For example, polymerization of a di- or polyisocyanate withitself in the presence of a suitable catalyst may be used to formpolyisocyanate dispersions (PID), or dispersions containing a variety ofisocyanate-derived linkages such as isocyanurate, allophanate,uretonimine, uretdione, carbodiimide and the like, often in associationwith reaction of a portion of the polyol continuous phase to introduceurethane linkages, or when an amino-functional species is present, urealinkages.

However, the preferred polymer-modified polyols are those prepared bythe in situ polymerization of a di- or polyisocyanate with anamino-functional monomer, preferably a diamino-functional monomer, or analkanolamine monomer, to form PHD and PIPA polymer-modified polyols.Preparation of polymer-modified polyols by reaction ofalkanolamine/isocyanate reaction mixtures in situ is described in U.S.Pat. Nos. 4,293,470; 4,296,213; 4,374,209; 4,452,923; and PCT publishedapplication WO 94/12553, all herein incorporated by reference. Ingeneral, a mono- to trialkanolamine having from two to about 8 carbonsin the alkanol residue such as ethanolamine, diethanolamine,triethanolamine, diisopropanolamine, triisopropanolamine,N-methylisopropanolamine, 2-(2-aminoethoxy)ethanol,hydroxyethylpiperazine, or the like is dissolved in a polyoxyalkylenebase polyol, and di- or polyisocyanate, preferably TDI or MDI is addeddropwise with stirring, during the course of which the temperaturegenerally rises to about 40°-50° C. Catalysts are generally unnecessary,although in some cases catalysts such as stannous octoate or dibutyltindilaurate may be added. The reaction is generally allowed to proceed fora period of from 0.5 to 2 hours, during the course of which a whitedispersion is obtained. In general, a portion of the polyol will alsoreact, as described in Goethals, Ed., TELECHELIC POLYMERS: SYNTHESIS ANDAPPLICATIONS, CRC Press, Inc., Boca Raton, Fla., © 1989, p. 211.

In PCT published application WO 94/12553 is disclosed an improved,substantially continuous process for preparing PIPA polyols with highsolids content and minimal viscosity. In the process disclosed, apolyoxyalkylene base polyol is mixed with a first alkanolamine such astriethanolamine, and fed to a high pressure mixhead calibrated toprovide the desired amount of isocyanate, preferably polymericdiphenylmethane di-isocyanate or an 80:20 mixture of 2,4- and2,6-toluenediisocyanates. A short time later, e.g. 5 seconds, a furtherquantity of alkanolamine, which may be the same or different from thefirst, is added to the reactive mixture in a second high pressuremixhead. By this process, stable, non-gelling, high solids dispersionsof useable viscosity are obtained with solids contents in some cases inexcess of 50% by weight.

PHD polymer-modified polyols are also preferred polymer-modifiedpolyols. Such polyols are described in Goethals, op.cit., U.S. Pat. Nos.3,325,421; 4,042,537; and 4,089,835; and also in M. A. Koshute et al.,"Second Generation PHD Polyol For Automotive Flexible Molding",POLYURETHANES WORLD CONGRESS, 1987--Sep. 29-Oct. 2, 1987, pp. 502-507;and K. G. Spider et al., "PHD Polyols, A New Class of PUR RawMaterials," J. CELL PLAS., January/February 1981, pp. 43-49, all hereinincorporated by reference.

In general, as with PIPA polyols, the isocyanate-reactive monomer, inthis case an amine or polyamine, is added to the base polyol. For amineswith low solubility, high speed stirring is used to form a finedispersion. Isocyanate is then added slowly, during the course of whichthe temperature will rise. Following a period of time to allow for fullreaction, a white, polyurea dispersion is obtained. The polymerparticles incorporate a portion of the polyol continuous phase.Preferred diamines are hydrazine and ethylenediamine, although otherdiamines as well as hydrazides, are useful. Preferred isocyanates arecommercial aromatic isocyanates such as methylene diphenylenediisocyanate, toluene diisocyanate, polyphenylene polymethylenepolyisocyanate, and the like, including modified isocyanates such asurethane-, urea-, carbodiimide-, uretdione-, uretonimine-, andallophanate-modified isocyanates. Aliphatic isocyanates such ashexamethylene diisocyanate and isophorone diisocyanate are also usefulin manufacturing PHD (and PIPA) polymer-modified polyols. Solids levelsof 10-40% or more are useful, in particular 10 or 20 to about 30%.Continuous processes, as disclosed in U.S. Pat. No. 4,089,835 areuseful.

The base polyol used for in situ polymerization to form polyol polymerdispersions should comprise in major part a polyoxyalkylene polyolcontaining a substantial quantity of oxypropylene moieties prepared inthe presence of an encapsulative double metal cyanide catalyst,preferably at least 5 ppm of which, calculated as Co and Zn or thecorresponding equivalents of other metals on a weight/weight basis,remain in the polyol. Preferably, this major component of the basepolyol is not subjected to catalyst removal treatment other than anoptional coarse filtration to remove gross particulates or by naturalsedimentation of catalyst residues in a non-agitated holding tank. Thismajor portion of polyoxyalkylene (>50 weight percent) may be mixed withother base polyol components such as conventionally catalyzedpolyoxyalkylene polyether polyols, polyester polyols, polyetheresterpolyols, and the like. However, if polyoxyalkylene polyols prepared fromnon-encapsulative double metal cyanide catalysts are used, either thenon-encapsulative double metal cyanide catalyst residues must besubstantially completely removed, or the amount of such polyolrestricted such that no more than 3-4 ppm non-encapsulative double metalcyanide complex catalyst residue calculated on the basis of Co and Zn ortheir other-metal equivalents is present in the base polyol. Thefunctionality of the polyoxyalkylene polyether polyol component mayrange from less than two, to eight or more, preferably from two to eightand more preferably from two to six. The functionality for any givenbase polyol component is dependent on the desired end use. For example,elastomers generally require low functionalities, e.g., two to three,while polyurethane foams generally require functionalities from 2.5 to4.0. "Functionality" as used herein is meant the mol average nominalfunctionality. "Nominal" functionality is the theoretical functionalitybased on the number of oxyalkylatable groups on the initiator molecule.

The hydroxyl number of the base polyol may range from about five to inexcess of 100, but is preferably within the range of 10-70, and morepreferably in the range of 20-60. Hydroxyl number may be measured inaccordance with ASTM D-2849-69. The hydroxyl number and functionality ofthe polyol polymer dispersion may be adjusted post manufacture by theaddition of polyols other than the base polyol used for the in situpolymerization. Solids contents of the polyol polymer dispersions rangefrom about 10 weight percent to about 60 weight percent or more based ontotal polymer polyol weight. Polymer polyols are preferably preparedwith solids contents in the higher ranges, i.e., 25 to 60 weightpercent, more preferably 30 to 50 weight percent, and reduced in solidscontent where appropriate by blending with additional polyol. In thismanner, reactor capacity and product throughput are maximized.Polymer-modified polyols generally contain somewhat lower levels ofsolids to limit viscosity of the polymer-modified polyol product. Solidscontents of from 10 to 50 weight percent, more preferably from 10 to 30weight percent are suitable.

Double metal cyanide complex catalyst sample x-ray diffraction spectrawere analyzed using monochromatized CuKα₁ radiation (λ=1.54059 Å). ASeimens D500 Kristalloflex diffractometer powered at 40 kV and 30 mA wasoperated in a step scan mode of 0.02° 2θ with a counting time of 2seconds/step. Divergence slits of 1° in conjunction with monochrometerand detector apertures of 0.05° and 0.15° respectively. Each sample wasrun from 5° to 70° 2θ. Water of hydration can cause minor variations inmeasured d-spacings.

The following procedures may be used to determine catalyst activity. Aone-liter stirred reactor is charged with polyoxypropylene triol (700mol. wt.) starter (70 g) and zinc hexacyanocobaltate catalyst (0.057 to0.143 g, 100-250 ppm level in finished polyol). The mixture is stirredand heated to 105° C. and is stripped under vacuum to remove traces ofwater from the triol starter. The reactor is pressurized to about 1 psiwith nitrogen. Propylene oxide (10-11 g) is added to the reactor in oneportion, and the reactor pressure monitored carefully. Additionalpropylene oxide is not added until an accelerated pressure drop occursin the reactor; the pressure drop is evidence that the catalyst hasbecome activated. When catalyst activation is verified, the remainingpropylene oxide (490 g) is added gradually over about 1-3 h at aconstant pressure of 20-24 psi. After propylene oxide addition iscomplete, the mixture is held at 105° C. until a constant pressure isobserved. Residual unreacted monomer is then stripped under vacuum fromthe polyol product, and the polyol is cooled and recovered.

The reaction rate is determined from a plot of PO consumption in gramsversus reaction time in minutes. The slope of the curve at its steepestpoint is measured to find the reaction rate in grams of PO converted perminute. The intersection of this line and a horizontal line extendedfrom the baseline of the curve is taken as the induction time (inminutes) required for the catalyst to become active.

Polyurethane foams, particularly water-blown flexible polyurethanefoams, are prepared by reacting a polyol component with an isocyanatecomponent. The polyol component often contains a polymer polyol orpolymer-modified polyol, with or without additional non-polymer polyol.In general, tin catalysts and amine catalysts are necessary to produce astable foam. It has been surprisingly discovered that when the polyolpolymer dispersions of the subject invention such as the PIPApolymer-modified polyols are used in the polyurethane foam polyolcomponent, the amount of catalyst, particularly tin catalyst, may belowered significantly while still producing a stable foam, as comparedwith otherwise similar formulations where polymer-modified polyolsprepared from conventionally catalyzed (basic catalysis) base polyolsare used to prepare the polymer-modified polyol. This unexpected resultallows greater processing latitude as well as being more cost effective.

Having generally described this invention, a further understanding canbe obtained by reference to certain specific examples which are providedherein for purposes of illustration only and are not intended to belimiting unless otherwise specified.

EXAMPLES 1-6 AND COMPARATIVE EXAMPLE 1 DOUBLE METAL CYANIDE CATALYSTPREPARATION Example 1

Potassium hexacyanocobaltate (8.0 g) is added to deionized water (150mL) in a beaker, and the mixture is blended with a homogenizer until thesolids dissolve. In a second beaker, zinc chloride (20 g) is dissolvedin deionized water (30 mL). The aqueous zinc chloride solution iscombined with the solution of the cobalt salt using a homogenizer tointimately mix the solutions. Immediately after combining the solutions,a mixture of tert-butyl alcohol (100 mL) and deionized water (100 mL) isadded slowly to the suspension of zinc hexacyanocobaltate, and themixture is homogenized for 10 min. The solids are isolated bycentrifugation, and are then homogenized for 10 min. with 250 mL of a70/30 (v:v) mixture of tert-butyl alcohol and deionized water. Thesolids are again isolated by centrifugation, and are finally homogenizedfor 10 min. with 250 mL of tert-butyl alcohol. The catalyst is isolatedby centrifugation, and is dried in a vacuum oven at 50° C. and 30 in.(Hg) to constant weight. The catalyst exhibits a propylene oxide initialpolymerization rate of 10.5 g propylene oxide/min. at 105° C. with acatalyst concentration of 250 ppm based on weight of product polyol,showed no sharp lines in the X-ray diffraction (XRD) spectrum atd-spacings of 5.07, 3.59, 2.54 and 2.28, and had a surface area of 14 m²/g.

Example 2

The procedure of Example 1 is modified as follows. Isopropyl alcohol issubstituted for tert-butyl alcohol. Following combination of the zincchloride and potassium hexacyanocobaltate solutions and homogenizationin the presence of isopropyl alcohol, the catalyst slurry is filteredthrough a 0.45 micron filter at 20 psi. The washing steps of Example 1are also repeated, but filtration rather than centrifugation is used toisolate the catalyst. The washed catalyst is dried to constant weight asdescribed above. The catalyst exhibits a propylene oxide initialpolymerization rate of 1.70 g/min. and exhibited the same lack of sharppeaks in the XRD spectrum as the catalyst of Example 1.

Example 3

Potassium hexacyanocobaltate (8.0 g) is dissolved in deionized (DI)water (140 mL) in a beaker (Solution 1). Zinc chloride (25 g) isdissolved in DI water (40 mL) in a second beaker (Solution 2). A thirdbeaker contains Solution 3: a mixture of DI water (200 mL), tert-butylalcohol (2 mL), and polyol (2 g of a 4000 mol. wt. polyoxypropylene diolprepared via double metal cyanide catalysis.

Solutions 1 and 2 are mixed together using a homogenizer. Immediately, a50/50 (by volume) mixture of tert-butyl alcohol and DI water (200 mLtotal) is added to the zinc hexacyanocobaltate mixture, and the productis homogenized for 10 min. Solution 3 (the polyol/water/tert-butylalcohol mixture) is added to the aqueous slurry of zinchexacyanocobaltate, and the product is stirred magnetically for 3 min.The mixture is filtered under pressure through a 5-μm filter to isolatethe solids.

The solid cake is reslurried in tert-butyl alcohol (140 mL), DI water(60 mL), and additional 4000 mol. wt. polyoxypropylene diol (2.0 g), andthe mixture is homogenized for 10 min. and filtered as described above,following which the solid cake is again reslurried in tert-butyl alcohol(200 mL) and additional 4000 mol. wt. polyoxypropylene diol (1.0 g),homogenized for 10 min., and filtered. The resulting solid catalyst isdried under vacuum at 50° C. (30 in. Hg) to constant weight. The yieldof dry, powdery catalyst is 10.7 g.

Elemental, thermogravimetric, and mass spectral analyses of the solidcatalyst show: polyol=21.5 wt. %; tert-butyl alcohol=7.0 wt. %;cobalt=11.5 wt. %. The catalyst exhibited a propylene oxidepolymerization rate of 3.3 Kg propylene oxide/g Co/min. and exhibitedthe same lack of sharp lines in the XRD spectrum as the catalysts ofExamples 1 and 2.

Example 4

A one-gallon glass pressure reactor is charged with a solution ofpotassium hexacyanocobaltate (40 g) in DI water (700 mL) (Solution 1).Zinc chloride (125 g) is dissolved in a beaker with DI water (200 mL)(Solution 2). Tert-butyl alcohol (500 mL) is dissolved in a beaker withDI water (500 mL) (Solution 3). A fourth mixture (Solution 4) isprepared by suspending a 4000 mol. wt. polyoxypropylene diol (60 g, sameas is used in Example 3) in DI water (1000 mL) and tert-butyl alcohol(10 mL).

Solutions 1 and 2 are combined with stirring at 3000 rpm followedimmediately by slow addition of Solution 3 to the resulting zinchexacyanocobaltate mixture. The stirring rate is increased to 900 rpm,and the mixture is stirred for 2 h at room temperature. The stirringrate is reduced to 300 rpm, and Solution 4 is added. The product ismixed for 5 min., and is filtered under pressure as described in Example1 to isolate the solid catalyst. The solids are reslurried in tert-butylalcohol (700 mL) and DI water (300 mL), and stirred at 900 rpm for 2 h.The stirring rate is reduced to 300 rpm, and 60 g of the 4000 mol. wt.polyoxypropylene diol is added. The mixture is stirred for 5 min., andis filtered as described above.

The solids are reslurried in tert-butyl alcohol (1000 mL) and stirred at900 rpm for 2 h. The stirring rate is reduced to 300 rpm, and 30 g ofthe 4000 mol. wt. polyoxypropylene diol is added. The mixture is stirredfor 5 min., and is filtered as described above. The resulting solidcatalyst is dried under vacuum at 50° C. (30 in. Hg) to constant weight.The catalyst is easily crushed to a fine, dry powder.

Elemental, thermogravimetric, and mass spectral analyses of the solidcatalyst show: polyol=45.8 wt. %; tert-butyl alcohol=7.4 wt. %;cobalt=6.9 wt. %. The catalyst exhibits a propylene oxide polymerizationrate of 6.69 g propylene oxide/g Co/min., and exhibited the same lack ofsharp peaks in the XRD spectrum as the catalysts of Examples 1-3.

Example 5

The procedure of Example 1 is followed, except that the 4000 mol. wt.polyoxypropylene diol is replaced with a 2000 mol. wt. polyoxypropylenediol also made using double metal cyanide catalysis.

Elemental, thermogravimetric, and mass spectral analyses of the solidcatalyst show: polyol=26.5 wt. %; tert-butyl alcohol=3.2 wt. %;cobalt=11.0 wt. %. The catalyst exhibited a propylene oxidepolymerization rate of 2.34 Kg propylene oxide/g Co/min., and exhibitedthe same lack of sharp peaks in the XRD spectrum as the catalysts ofExamples 1-4.

Example 6

Example 4 is repeated, except that a 4000 Da diol end-capped withisobutylene oxide to provide c.a. 50% tertiary hydroxyl groups is used.The catalyst exhibited higher activity than the catalyst of Example 4.

Comparative Example 1

This example demonstrates the preparation of a non-encapsulative doublemetal cyanide complex catalyst. A solution of zinc chloride (26.65 g;0.1956 mol) in water (26.65 g) is added rapidly to a well-agitatedsolution of potassium hexacyanocobaltate (13.00 g 0.0391 mol) in water(263.35 g). The potassium hexacyanocobaltate solution is maintained at40° C. during addition of the zinc chloride solution. A whiteprecipitate of zinc hexacyanocobaltate particles forms immediately uponaddition. After stirring for 15 minutes at 40° C., dimethoxyethane(glyme) (84.00 g; 0.9321 mol) is added to the aqueous catalyst slurry.The resulting mixture is stirred for an additional 30 minutes and thezinc hexacyanocobaltate.dimethoxyethane water complex catalyst recoveredby filtration using a horizontal basket centrifugal filter and a lightweight nylon fabric filter medium. The filtration rate was relativelyfast with minimal clogging of the pores of the filter medium. Afterwashing with 300 mL dimethoxyethane and drying in air at ambienttemperature and pressure, the filter cake obtained is quite soft and canbe easily crushed to a fine powder.

The catalyst exhibits a propylene oxide polymerization rate of 3.50 gpropylene oxide/min.

EXAMPLES 7-15 AND COMPARATIVE EXAMPLES 2-4 POLYOXYALKYLENE POLYETHERPOLYOL SYNTHESIS

A two-gallon stirred reactor is charged with polyoxypropylene triol (700mol. wt.) starter (685 g) and zinc hexacyanocobaltate catalyst (1.63 g).The mixture is stirred and heated to 105° C., and is stripped undervacuum to remove traces of water from the triol starter. Propylene oxide(102 g) is fed to the reactor, initially under a vacuum of 30 in. (Hg),and the reactor pressure is monitored carefully. Additional propyleneoxide is not added until an accelerated pressure drop occurs in thereactor; the pressure drop is evidence that the catalyst has becomeactivated. When catalyst activation is verified, the remaining propyleneoxide (5713 g) is added gradually over about 2 h while maintaining areactor pressure less than 40 psi. After propylene oxide addition iscomplete, the mixture is held at 105° C. until a constant pressure isobserved. Residual unreacted monomer is then stripped under vacuum fromthe polyol product. When catalyst removal is desired, the hot polyolproduct is filtered at 100° C. through a filter cartridge (0.45 to 1.2microns) attached to the bottom of the reactor to remove the catalyst.Residual Zn and Co are quantified by X-ray analysis.

Polyether diols (from polypropylene glycol starter, 450 mol. wt.) andtriols are prepared as described above using both encapsulative andnon-encapsulative zinc hexacyanocobaltate catalysts. The polyolunsaturation of the polyols produced is presented in Table I.

                  TABLE I                                                         ______________________________________                                                                           Polyol                                                           Hydroxyl Number                                                                            Unsaturation                               Example    Catalyst   and Functionality                                                                          (meq/g)                                    ______________________________________                                        Comparative Exam-                                                                        Comparative                                                                              54 (Triol)   0.016                                      ples 2, 3 & 4                                                                            Example 1  27 (Triol)   0.017                                                            15 (Triol)   0.019                                      Example 7  Example 1  27 (Triol)   0.005                                      Example 8             56 (Diol).sup.                                                                             0.004                                      Example 9             27 (Diol).sup.                                                                             0.005                                      Example 10            14 (Diol).sup.                                                                             0.004                                      Example 11 Example 3  30 (Triol)   0.006                                      Example 12 Example 4  29 (Triol)   0.004                                      Example 13 Example 5  31 (Triol)   0.004                                      Example 14 Example 6  14 (Diol).sup.                                                                             0.005                                      Example 15 Example 6  28 (Triol)   0.004                                      ______________________________________                                    

EXAMPLES 16-21 AND COMPARATIVE EXAMPLE 5

Polymer polyols are prepared in a continuous process, in each caseemploying a preformed stabilizer prepared by capping a maleicanhydride/polyoxypropylene polyol half ester with ethylene oxide andisomerizing the maleate unsaturation to fumarate in the presence ofmorpholine. The preparation of the preformed stabilizer is in accordancewith Example 1 of U.S. Pat. No. 5,268,418, herein incorporated byreference.

A continuous polymerization system was used, employing a tank reactorfitted with baffles and an impeller. The feed components were pumpedinto the reactor continuously after going through an inline mixer toassure complete mixing of the feed components before entering thereactor. The internal temperature of the reactor was controlled towithin ±1° C. at 115° C. The contents of the reactor were well mixed.The product flowed out the top of the reactor and into a secondunagitated reactor also controlled within 1° C. The product then flowedout the top of the second reactor continuously through a back pressureregulator adjusted to give about 45 psig pressure on both reactors. Thecrude product then flowed through a cooler into a collection vessel.Percent by weight polymer in the polymer polyol was determined fromanalysis of the amount of unreacted monomers present in the crudeproduct. The crude product was vacuum stripped to remove volatilesbefore testing. All of the polymer polyols were stable compositions. Ineach Example, the feed rates in parts per hour were as follows: polyol,236.2; preformed stabilizer 25.2; catalyst (AIBN), 1.5; acrylonitrile,60.9; styrene, 142.1.

The polyols utilized were prepared in accordance with the foregoingExamples. Polyoxyalkylene content, type (triol, diol), hydroxyl numbers,catalyst type, catalyst concentration during polyol preparation arepresented in Table II, as are the polymer solids of the resultingpolymer polyols, the initial Zn/Co concentrations in the polyol used toprepare the polymer polyol, the Zn/Co concentrations in the polymerpolyol (continuous plus dispersed phases) and the Zn/Co concentrationsin the polyol (continuous) phase alone.

                                      TABLE II                                    __________________________________________________________________________                                            Zn/Co in                                    Base Polyol                                                                           Base Polyol Zn/Co in Base                                                                        Zn/Co in                                                                             Polymer                                     Catalyst Type                                                                         Hydroxyl/                                                                           Base Polyol                                                                         Polyol As Used                                                                       Polymer Polyol                                                                       Continuous                                                                          Polymer Wt.                     Example                                                                             (Amount, ppm)                                                                         Type  Composition                                                                         (ppm)  (ppm)  Phase (ppm)                                                                         Solids, %                       __________________________________________________________________________    Comparative                                                                         Comparative                                                                           47.2/Triol                                                                          10% EO                                                                              30/13  18/8   8/8   44.6                            Example 5                                                                           Example 1 (125)                                                                             random                                                    16    Example 1 (250)                                                                       27.1/Diol                                                                           0% EO 47/16.sup.2                                                                          27/10  2/<1  44.8                            17    Example 3 (25)                                                                        51.8/Triol                                                                          12% EO                                                                              2/1.sup.1                                                                            <1/<1  <1/<1 45.1                                                random                                                    18    Example 1 (25)                                                                        51.7/Triol                                                                          12% EO                                                                              5/2    1.5/<1 <1/<1 45.8                                                random                                                    19    Example 1 (25)                                                                        51.7/Triol                                                                          12% EO                                                                              2.8/1.5.sup.1                                                                        2.1/1.1                                                                              <1/<1 45.3                                                random                                                    20    Example 3 (25)                                                                        52.1/Triol                                                                          12% EO                                                                              4/2    1.7/<1 <1/<1 45.4                                                random                                                    21    Example 3 (25)                                                                        56.8/Triol                                                                          12% EO                                                                              3/2    2.2/<1 <1/<1 44.9                                                random                                                    __________________________________________________________________________     .sup.1 Base polyol was filtered after preparation to remove a substantial     portion of catalyst residue prior to use in preparing polymer polyol.         .sup.2 Base polyol was not filtered to remove catalyst residue, but           portion of residue had settled out. Supernatent was used for polymer          polyol preparation.                                                      

As can be seen from Table II, the preparation of polymer polyols frombase polyols prepared using prior art double metal cyanide-glymecatalyst, a non-encapsulative double metal cyanide catalyst (ComparativeExample 5) showed little reduction in Zn/Co content in the polymerpolyol continuous phase despite starting with a relatively low Zn/Cocontent for this type of catalyzed polyol (Zn/Co=30/13). However, whenpolymer polyols were prepared using encapsulative double metal cyanidecatalysts (Examples 16-21), in each case, substantial reductions ofZn/Co content, generally to levels below the level of detection of c.a.1 ppm, were obtained, even in the case of high initial transition metalcontent as is the case for Example 16. Such polyols are useful innumerous applications where polyols with higher Zn/Co content areunsuitable.

EXAMPLES 22-23 POLYMER-MODIFIED POLYOL SYNTHESIS Example 22

To 900 g of a trifunctional polyoxyalkylene polyol having a hydroxylnumber of 35, a primary hydroxyl content of 13 percent, and anunsaturation of c.a. 0.0062 meq/g, prepared by the encapsulative doublemetal cyanide complex catalyzed oxyalkylation of a glycerine-initiatedoligomer containing residual double metal cyanide catalyst residues isadded 48.7 g triethanolamine at a temperature of c.a. 25° C. Followingthorough mixing, the agitator is turned up to high speed and 51.7 gtoluene diisocyanate is added over a period of approximately 5 secondsunder a nitrogen blanket. To the mixture is then added 0.3 g T-12 tincatalyst dissolved in a minor amount of additional polyol. Thetemperature rises to c.a. 40° C., following which the reaction mixtureis stirred under slow speed until cooled. The base polyol used toprepare the polymer-modified polyol contained 6.7 ppm Zn and 2.8 ppm Co.A white dispersion is obtained having catalyst residues concentrated inthe dispersed phase, the concentrations of Zn and Co in the continuouspolyol phase being only 0.5 ppm and <0.2 ppm, respectively.

Example 23

The process of Example 22 is repeated, but with the reactor chargesbeing 1000 g polyol, 230 g triethanolamine, and 0.03 g T-12 tincatalyst. Following thorough mixing and heating to 54° C., the agitationspeed is increased to high and 271.0 g toluene diisocyanate added over aperiod of 5 seconds. The temperature rapidly rises and reaches a maximumof about 105° C. Approximately 10 seconds after isocyanate addition, 50g DEOA-LF (diethanolamine low freezing) is added, following which thereaction is allowed to cool with slow agitation. A white, high solidsPIPA polymer-modified polyol dispersion is obtained with transitionmetal content concentrated in the dispersed polymer phase.

Comparative Example 6

A polymer-modified polyol was prepared as in Example 22, using the sameproportions of reactants, but employing a conventional base-catalyzedbase polyol having a hydroxyl number of 35 and a level of unsaturationof 0.027 meq/g.

EXAMPLES 24-25 AND COMPARATIVE EXAMPLES 7 and 8 Polyurethane FoamPreparation

A series of all water-blown polyurethane foams were prepared from thesubject invention polymer-modified polyols synthesized in accordancewith Examples 22 and 23 and a conventional polymer-modified polyolsynthesized in accordance with Comparative Example 6. The formulationsand foam quality are indicated in Table III below.

                                      TABLE III                                   __________________________________________________________________________    Polymer-Modified                                                                             Example 24                                                                          Example 25                                                                          Comparative Example 7                                                                    Comparative Example 8                   Polyol From Example                                                                          22    23    C-6        C-6                                     __________________________________________________________________________    Base Polyol                                                                   Unsaturation, meq/g                                                                          0.0062                                                                              0.0062                                                                              0.027.sup.1                                                                              0.027.sup.1                             OH, %          35    35    35         35                                      Primary OH, %  13    13    7          7                                       Polymer-Modified Polyol                                                       Based Polyol, g                                                                              900   1000  900        900                                     Triethanolamine                                                                              48.7  230   48.7       48.7                                    Tolylene Diisocyanate, g                                                                     51.7  271.0 51.7       51.7                                    Dibutyl-tin-dilaurate, g                                                                     0.3   0.03  0.3        0.3                                     Diethanolamine (low freezing), g                                                             --    50    --         --                                      Formulation for Foam                                                          PIPA Polyol, g 100   100   100        100                                     DEOA-LF, g     1.18  1.18  1.18       1.18                                    B-8707 silicone, g                                                                           0.5   0.5   0.5        0.5                                     Water, g       2.42  2.42  2.42       2.42                                    A-1 amine catalyst, g                                                                        0.11  0.11  0.11       0.11                                    T-12 tin catalyst, g                                                                         0.07  0.07  0.07       0.25                                    TDI, g         39    39    39         39                                      Foam Appearance                                                                              Good  Good  Collapses  Very Porous                             __________________________________________________________________________     .sup.1 Conventional basecatalyzed base polyol.                           

As can be seen, both the polymer-modified polyols of the subjectinvention (from Examples 22 and 23) employing low-unsaturation basepolyols, foamed well at 0.07 parts tin catalyst per 100 parts polyol,while polymer-modified polyols prepared from conventionally catalyzedbase polyols (from Comparative Example 6) did not produce a stable foamat the same catalyst concentration, the foam exhibiting collapse, andproduced only a poor quality, very porous foam even at a tin catalystlevel higher by a factor of almost four. These results are totallyunexpected.

Having now fully described the invention, it will be apparent to one ofordinary skill in the art that many changes and modifications can bemade thereto without departing from the spirit or scope of the inventionas set forth herein.

What is claimed is:
 1. A method of substantially eliminating transitionmetal content in the continuous phase of a polyol polymer dispersionprepared by the in situ polymerization of one or more polymerizablemonomers in a base polyol comprising in pan one or more double metalcyanide complex-catalyzed polyoxyalkylene polyether polyols, said basepolyol containing transition metals derived from said double metalcyanide complex catalyst, said method comprising:a) selecting as saidbase polyol a base polyol comprising one or more polyoxyalkylenepolyether polyols prepared by the oxyalkylation of one or moreoxyalkylation initiator molecules with propylene oxide, optionally inconjunction with one or more alkylene oxides other than propylene oxide,in the presence of an encapsulative double metal cyanide complexcatalyst, said base polyol containing transition metals derived fromsaid encapsulative double metal cyanide complex catalyst; b)polymerizing one or more polymerizable monomers in said base polyol toform a polyol polymer dispersion having a continuous polyol phase and adispersed phase comprising polymer particles associated with saidtransition metals; and c) recovering a polyol polymer dispersion havingtransition metals substantially removed from said continuous polyolphase.
 2. The method of claim 1 wherein said continuous polyol phasecontains less than 4 ppm of total transition metals calculated on thebasis of a hypothetical transition metal atomic weight of
 62. 3. Themethod of claim 1 wherein each transition metal contained in saidcontinuous polyol phase is present in an amount less than or equal to 2ppm based on the weight of said continuous polyol phase.
 4. The methodof claim 2 wherein said base polyol contains about 20 ppm or more oftransition metals based on the weight of said base polyol.
 5. The methodof claim 3 wherein said base polyol contains about 20 ppm or more oftransition metals based on the weight of said base polyol.
 6. The methodof claim 1 wherein said encapsulative double metal cyanide complexcatalyst is an encapsulative zinc hexacyanocobaltate complex catalyst.7. The method of claim 6 wherein said zinc hexacyanocobaltate complexcatalyst contains complexing agents selected from the group consistingof t-butanol, and t-butanol together with a polyoxyalkylene polyetherpolyol having an equivalent weight of greater than 200 Da.
 8. The methodof claim 1, wherein at least about 75 weight percent of the totaltransition metal content of said base polyol is associated with saiddispersed phase.
 9. The method of claim 1 wherein said encapsulativedouble metal cyanide complex-catalyzed polyoxyalkylene polyether polyolsare not treated to remove catalyst residues prior to in situpolymerization of polymerizable monomers.
 10. The method of claim 1wherein said encapsulative double metal cyanide-catalyzedpolyoxyalkylene polyether polyol is filtered prior to in situpolymerization of polymerizable monomers, said filtered polyol yetcontaining greater than 2 ppm transition metal content based on theweight of said filtered polyol.
 11. The method of claim 1 wherein aportion of transition metals are removed from said encapsulative doublemetal cyanide complex catalyzed polyoxyalkylene polyether polyol byallowing catalyst or catalyst residues to sediment from storedpolyoxyalkylene polyether polyol and selecting as a portion of said basepolyol a supernatant of said stored polyoxyalkylene polyether polyol.12. The method of claim 1 further comprising a non-encapsulative doublemetal cyanide complex-catalyzed polyoxyalkylene polyether polyol,wherein said base polyol contains not more than 4 ppm total transitionmetals derived from said non-encapsulative double metal cyanide complexcatalyst based on the weight of said base polyol.
 13. The method ofclaim 1 wherein said encapsulative double metal cyanide complex catalystis a substantially amorphous zinc hexacyanocobaltate complex catalystexhibiting substantially no sharp peak in an X-ray diffraction patternat a d-spacing of approximately 5.1.
 14. The method of claim 1 whereinsaid polymerizable monomers comprise one or more vinyl monomers.
 15. Themethod of claim 14 wherein said one or more vinyl monomers compriseacrylonitrile, styrene, or mixtures thereof.